Due to the cyclic behaviour of the complex numbers, we have that for any .

The next step is to take cube root of both sides, so that exponent becomes (omitting the , but it's still there). Since , the expression reduces to what you're uncertain about with the sufficient condition that in order to capture all the roots.

Due to the cyclic behaviour of the complex numbers, we have that for any .

The next step is to take cube root of both sides, so that exponent becomes (omitting the , but it's still there). Since , the expression reduces to what you're uncertain about with the sufficient condition that in order to capture all the roots.